[CP-1742] fixes after QA

[wojcik92michal]

Jira: CP-1742

Description
This PR cover three cases discovered by QA team:

• displaying "checking for update failed" label (see attached image)
• "check for update" modal may start to install update (this happen in very peculiar condition - see https://appnroll.atlassian.net/browse/CP-1742?focusedCommentId=69995 and 4th point from the comment) - see attached image
• "silent check" now works fine for unplugging cable

Screenshots

Nagranie.z.ekranu.2023-01-18.o.08.35.27.mov

[codecov]

Codecov Report

Base: 77.52% // Head: 77.62% // Increases project coverage by +0.09% 🎉

Coverage data is based on head (3b47dfa) compared to base (27c2631).
Patch coverage: 90.21% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1089      +/-   ##
==========================================
+ Coverage   77.52%   77.62%   +0.09%     
==========================================
  Files         867      870       +3     
  Lines       12291    12352      +61     
  Branches     1784     1794      +10     
==========================================
+ Hits         9529     9588      +59     
- Misses       2296     2298       +2     
  Partials      466      466              

Impacted Files	Coverage Δ
...ailable-modal/update-available-modal.component.tsx	80.00% <57.14%> (-9.48%)	⬇️
...-screens/pure-overview/pure-overview.component.tsx	79.86% <75.00%> (+0.67%)	⬆️
...ns/harmony-overview/harmony-overview.component.tsx	81.81% <87.50%> (+0.80%)	⬆️
...ns/harmony-overview/overview-content.component.tsx	100.00% <100.00%> (ø)
...iew-screens/helpers/use-update-flow-state.hook.tsx	100.00% <100.00%> (ø)
...reens/pure-overview/overview-content.component.tsx	100.00% <100.00%> (ø)
...rc/overview/components/system-update-text/index.ts	100.00% <100.00%> (ø)
...ystem-update-text/system-update-text.component.tsx	100.00% <100.00%> (ø)
...rc/overview/components/system/system.component.tsx	95.65% <100.00%> (-0.78%)	⬇️
...onents/update-os-flow/update-os-flow.component.tsx	91.46% <100.00%> (+0.10%)	⬆️
... and 1 more

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